The candidate has significant research experience, including a Ph.D. in pharmacology investigating signal transduction during cell differentiation, and current work developing inhibitors to E2F transcription factors. He will complete fellowship training in Medical Oncology and become a full-time faculty member of the Division of Geriatrics at Duke University. The candidate will work in the rich scientific environment of Duke University and the Durham VA Medical Centers under the mentorship of Joseph Nevins, Ph.D., a leader in the study of cell growth control, Miriam Smyth, Ph.D., who has experience in aging biology, and Harvey Cohen, M.D., who will provide career development guidance. The proposed research will provide the candidate new experience in cellular senescence, and extend his current work on cell cycle control. This research will allow development of an independent research laboratory from which clinically pertinent basic research questions can be pursued. Cellular senescence involves a G1 cell cycle proliferative block and E2F is of fundamental importance in bypassing G1 block in other systems. The hypothesis of this proposal is that individual E2F family members play distinct, important roles in the G1 cell cycle block in cellular senescence. Aim I proposes to measure activity and complexes of individual E2Fs by gel shift assay. E2F expression will be measured by Western, Northern and nuclear run-off analysis as cells senesce. Transcriptional regulation of E2F in senescent cells will be addressed by mutational analysis. Aim II proposes to induce DNA synthesis in senescent cells by adenovirus mediated expression of E2Fs, or delay senescence by stable E2F expression. The effect of inhibiting E2Fs with E2F-binding RNA ligands on proliferating cell phenotype will be measured. Mouse embryo fibroblasts with E2F genes knocked out will be evaluated for their ability to senesce and bypass crisis. Aim III proposes to use DNA filter arrays to identify new E2F targets that may play an important role in the senescent phenotype. In summary the research described in this proposal is critical to understanding the molecular basis for senescent cell growth arrest. Given the research environment, mentors and career development plan, this candidate will develop into a sound independent scientist.